The kilogram is dead: Long live the kilogram

It appears the kilogram as a physical reference object is going the way of the meter, being replaced by derivation of a constant in nature.

What this means for you and me? Absolutely nothing. But I like knowing things and I'm sure there are others that do as well.

This week, scientists will meet to redefine the world’s weights

A lump of metal defines the world’s system of weights — but that changes this week

https://www.theverge.com/2018/11/13/18087002/kilogram-new-definition-kg-metric-unit-ipk-measurement

Hmmm.... VERY interesting to this old-fart-chemistry prof. I thought NIST was looking at a silicon sphere as the definition. The roundest and probably purest object ever made; one copper atom per three billion silicon atoms, and so round that if it was the size of the Earth, the highest and lowest points would differ by about three meters:
https://www.chemistryworld.com/news...ed-will-redefine-the-kilogram/3007588.article

Best -- Terry

Oh, heck, it is time for me to retire. Medicine, in the US, just moved to Kgs recently and now they want me to learn something else.

YUP, time to retire. When they change to Kilograms, that was listed as one of the number one cause of medical errors. I guess I got lucky and either know math or it was just plan old luck.

prfesser said:

Hmmm.... VERY interesting to this old-fart-chemistry prof. I thought NIST was looking at a silicon sphere as the definition. The roundest and probably purest object ever made; one copper atom per three billion silicon atoms, and so round that if it was the size of the Earth, the highest and lowest points would differ by about three meters:
https://www.chemistryworld.com/news...ed-will-redefine-the-kilogram/3007588.article

Best -- Terry

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They were - along with the Russians, IIRC. I think they had machining problems. Looks like the people taking the Plank approach were able to make the more reliable measurements to date.

Nytrunner said:

I
...What this means for you and me? Absolutely nothing. But I like knowing things and I'm sure there are others that do as well.

>snip<

https://www.theverge.com/2018/11/13/18087002/kilogram-new-definition-kg-metric-unit-ipk-measurement

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That it is a fairly annoying article. And not just because they fouled the Lord Kelvin Quote. Which was (almost) taken from a talk about the generally poor procedures for defining electrical units of measurement at the end of the 19th century.

https://archive.org/stream/popularlecturesa01kelvuoft#page/73/mode/1up

cwbullet said:

Oh, heck, it is time for me to retire. Medicine, in the US, just moved to Kgs recently and now they want me to learn something else.

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They aren't abandoning the kilogram (gram) as a unit. They are changing the definition and realization of the unit.

From this

https://www.bipm.org/utils/common/documents/jcgm/JCGM_200_2012.pdf



It won't mean much to folks shopping for bananas -- nor is it even likely to mean the difference between an effective dose and a lethal dose of some drug -- but it will make a difference for the folks who are synthesizing the drugs or trying to save the banana.

Of course, most rocketeers in the US will continue to measure their rockets using "3 barley corns" for length and "7000 grains of barley drawn from the center of the ear" for weight (and woe betide the flier who records the weight of a rocket in "newtons" on a flight card) <smile>

edit: sorry for time traveling -- I somehow made the quoted explanation of the realization of units disappear while trying to change the indentation.

prfesser said:

Hmmm.... VERY interesting to this old-fart-chemistry prof. I thought NIST was looking at a silicon sphere as the definition. The roundest and probably purest object ever made; one copper atom per three billion silicon atoms, and so round that if it was the size of the Earth, the highest and lowest points would differ by about three meters:
https://www.chemistryworld.com/news...ed-will-redefine-the-kilogram/3007588.article

Best -- Terry

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That sounds like a manufacturing nightmare

cwbullet said:

Oh, heck, it is time for me to retire. Medicine, in the US, just moved to Kgs recently and now they want me to learn something else.

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What was the unit beforehand? I recall medicine in milligrams and milliliters since I was a kid in the 90s (some were oz, and of course cc's)

jlabrasca said:

Of course, most rocketeers in the US will continue to measure their rockets using "3 barley corns" for length and "7000 grains of barley drawn from the center of the ear" for weight (and woe betide the flier who records the weight of a rocket in "newtons" on a flight card) <smile>

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Lol, that reminds me of a time launch control read this guy's flight card "....and his rocket weighs an asTounding Four thousand, Three hundred and Fifty(!)........grams"

We used pounds and F for weight and temp. We did use ml and mg from meds.

Nytrunner said:

That sounds like a manufacturing nightmare

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Not as much as you might think. Two surfaces with abrasives between them, rubbed back and forth and around randomly, can essentially take only one of two forms: both planar, or concave and convex spherical. Amateur astronomers (me too!) have taken advantage of this behavior to make many a reflecting telescope mirror.

In any event, the defined standard doesn't need to be replicated all the time, it just needs to be reproducible to the necessary precision.

Best -- Terry

cwbullet said:

We used pounds and F for weight and temp. We did use ml and mg from meds.

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Oh so they're going to list body weight as kilograms now? Hmmm, so 90% of the time they'll need to convert when the patient gives their weight in pounds.

Who knows, maybe that'll slowly help develop metric familiarity in the population. I love metric for calculations, but I still have a better sense of things in pounds and feet vs kilograms and meters in everyday life because I live in the US. Have you ever seen the light in a foreign business visitor or tourist's eyes when you express something in metric terms?

Nytrunner said:

Oh so they're going to list body weight as kilograms now? Hmmm, so 90% of the time they'll need to convert when the patient gives their weight in pounds.

Who knows, maybe that'll slowly help develop metric familiarity in the population. I love metric for calculations, but I still have a better sense of things in pounds and feet vs kilograms and meters in everyday life because I live in the US. Have you ever seen the light in a foreign business visitor or tourist's eyes when you express something in metric terms?

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I used to make a joke about "familiarity" in class, teasing students that they all understood "liters" at the convenience store soda fountain, but not at the gas pump -- and asking them to think of a context in which "grams" were commonly used. It generally got a few laughs or, at least, smiles.

Since legalization for recreational use, there are signs for "$15 grams" all over town and the joke isn't as compelling.

The °F to °C transition is harder -- I suspect because we cannot compare temperatures by sight the way that we can compare lengths and volumes (and, by comparing volumes of a single material, masses). We know what kind of number means a "hot day" or " cold day" -- but the size of the unit is just a number, not a sensible quantity.

I should probably explain. Medication dosing for years has been per pound for years. About 8 years ago, there was a big push to transition to Celsius and metric. We are finally there. I was joking that they will change it once I finally got my 1200 provider all using metrics. I realize the article was mostly in gest.

I personally thing it is time to transition 100% of the US to metric.

When I went to paramedic school in the late 80s we did everything in metric - plus the conversion on weight (we used 2.2 pounds = 1 kg, so a 100kg patient = 220 pounds). All our meds by weight were done in mg/kg or mcg/kg. It is also important to remember we just needed to be in the ball park. All of our patient weights were 'guess-timates' and some medics were better at it than others.

I do find it fascinating the way we rocketeers mix and match metric and imperial. We have 18mm or 24mm motors and body tube diameters, but we use parachutes that are 18-inches in diameter and body tubes that are 15-inches long

Bob Austin - We were taught the same in our medic school 10 years ago. As you observed l, some medics are better estimating weight and conversions than others. We dose all of our meds using metric system and some are dosed by the patients weight in kilograms, so for now, many of us need to be familiar with imperial and metric systems. One of my biggest pet peeves is a trend where orders and protocols are written to administer drugs, not fluids, by volume based on an assumed concentration whenever it was packaged. Some say it reduces med errors when drawing up meds, I say it is dangerous since we shouldn't assume we always have the same concentration prepared in our kits.

NateB said:

One of my biggest pet peeves is a trend where orders and protocols are written to administer drugs, not fluids, by volume based on an assumed concentration whenever it was packaged. Some say it reduces med errors when drawing up meds, I say it is dangerous since we shouldn't assume we always have the same concentration prepared in our kits.

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Reminds me of a paramedic student I was proctoring many years ago. I asked how much of the drug he should administer - his answer was "1 amp". Ummmm - no. You are correct that folks need to not only know how to do this, but practice it. I retired from clinical a couple years ago, but still teach the emergency management aspect. One problem that is becoming consistent is that:

• When the computers go down, many of the newer/younger providers have no idea how to document their care on paper forms
• When the power goes out and the IV pumps stop working, providers don't know how to calculate drip rates by hand.

This kinda stuff is not a 'nice to know' but a 'need to know'. You are absolutely correct.

jlabrasca said:

We know what kind of number means a "hot day" or " cold day"

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Changeover for me was during primary school (1973). We were taught: Frosty fives, tingly tens, temperate twenties, thirsty thirites, frying forties. That quickly helped us get a handle on the scaling.

NateB said:

One of my biggest pet peeves is a trend where orders and protocols are written to administer drugs, not fluids, by volume based on an assumed concentration whenever it was packaged. Some say it reduces med errors when drawing up meds, I say it is dangerous since we shouldn't assume we always have the same concentration prepared in our kits.

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I don't think they have thought that one through very well. Big assumption.

Bob Austin said:

When the power goes out and the IV pumps stop working, providers don't know how to calculate drip rates by hand.

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My wife teaches nursing, and I can do these dose calculations standing on my head, whichever way they want the drugs delivered or however they are supplied. It is amazing, and scary, to see future nurses struggle with the basics of this. I really wonder if it is due to how maths is taught in secondary school these days, or something.


Resistance is Futile: Go Metric!
You really will love it, although you will have some weird imperial threads hanging around for centuries, based on my personal experience .

Here in Canada, we've been taught in metric (~1978) and I work in a European company where metric rules. But all our materials comes in feet and pounds. Of course there is metric conversions, and almost everybody knows when they buy 454 grams of butter; it's a pound. Some things never changed since the conversion to metric system; 2x4 lumbers, 4'x8' plywood sheet etc... I can see older people still talking in feet-pounds-fahrenheit, while my generation and specifically the one after mine, are clever with the metric system. One thing that I like with the metric system, is that every measure is dividable or multipliable by 10.

OverTheTop said:

Changeover for me was during primary school (1973). We were taught: Frosty fives, tingly tens, temperate twenties, thirsty thirites, frying forties. That quickly helped us get a handle on the scaling.

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I like that. Thanks.

Bob Austin said:

When I went to paramedic school in the late 80s we did everything in metric - plus the conversion on weight (we used 2.2 pounds = 1 kg, so a 100kg patient = 220 pounds). All our meds by weight were done in mg/kg or mcg/kg. It is also important to remember we just needed to be in the ball park. All of our patient weights were 'guess-timates' and some medics were better at it than others.

I do find it fascinating the way we rocketeers mix and match metric and imperial. We have 18mm or 24mm motors and body tube diameters, but we use parachutes that are 18-inches in diameter and body tubes that are 15-inches long

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That is my experience also, but in the last 8, they stopped using pounds in most facilities and no longer use F temps.

OverTheTop said:

It is amazing, and scary, to see future nurses struggle with the basics of this. I really wonder if it is due to how maths is taught in secondary school these days, or something.

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It might be, it also might be a hospital's fear of lawsuits for mistakes. We have IV pumps that are connected to the network. They won't allow you to administer a med outside the parameters ordered by the physician without overriding several steps. It seems that some newer nurses never learn to do any drug calculations manually. They then struggle when computers are down and don't immediately recognize an order that was inappropriate or a mistake.

In my case, we respond to many different hospitals and EMS systems across a large distance. It isn't always practice to take the time to change all the meds over to our supply, so we end up using a variety of preparations using then IV pumps we stock or drawing meds into syringe pumps when tubing isn't compatible with our equipment. We can't rely on the computer to help our doses since we don't have libraries for every facility we may respond to. I worry it will be a challenge to retrain new employees who were never taught drug calculations manually.

Construction is where the biggest resistance to metric in the US will probably be, most if not nearly all of our construction material manufacturers would need to retool extensively to manufacture things like plywood, concrete block, and many other items to cut down on material wastage using imperial based materials in metric consruction.

cwbullet said:

That is my experience also, but in the last 8, they stopped using pounds in most facilities and no longer use F temps.

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We see both. Some facilities will even list patient weight in kgs and their temps in F.

NateB said:

It might be, it also might be a hospital's fear of lawsuits for mistakes. We have IV pumps that are connected to the network. They won't allow you to administer a med outside the parameters ordered by the physician without overriding several steps. It seems that some newer nurses never learn to do any drug calculations manually. They then struggle when computers are down and don't immediately recognize an order that was inappropriate or a mistake.

In my case, we respond to many different hospitals and EMS systems across a large distance. It isn't always practice to take the time to change all the meds over to our supply, so we end up using a variety of preparations using then IV pumps we stock or drawing meds into syringe pumps when tubing isn't compatible with our equipment. We can't rely on the computer to help our doses since we don't have libraries for every facility we may respond to. I worry it will be a challenge to retrain new employees who were never taught drug calculations manually.

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The same is true with young physicians, Pas, pharmacists, etc. Put them in an austere environment without the internet and a computer and they struggle. I can revert back to paper charting and math in my head in a heartbeat. I guess I complain about metric but I can handle it. The celcius temps are little new but I can readily convert them.

rharshberger said:

Construction is where the biggest resistance to metric in the US will probably be, most if not nearly all of our construction material manufacturers would need to retool extensively to manufacture things like plywood, concrete block, and many other items to cut down on material wastage using imperial based materials in metric consruction.

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That's an interesting point. I think you may be correct, but I don't know if re-tooling the factories would be the issue.

As a frequent viewer of How Its Made, (and also someone who worked as a process development engineer in a high volume manufacturing environment) I don't guess that maintaining sets of metric-sized extrusion die for bricks and block would represent much increase in cost-of-ownership.

I'd also guess that plywood would be one of the easier things to deal with -- half inch ply is just about 12 mm thick and 122 cm by 244 cm is near enough 4' x 8'. In fact, its so close that it probably doesn't need to be changed (nominal dimensions are frequently different from actual). And if it did make sense to round to the nearest millimeter, its a continuous production process. It'd be a matter of changing the set and timing on the cut-off saws.

I think the resistance might be stronger from the trades who have to use the metric-dimensioned materials. Particularly if they had to move between metric and imperial dimensions on site.

After decades of habituation, I tend to think in SI units. To the point that it takes real effort to for me understand lengths in fractional inches (also have trouble with weights in oz). It has made for some frustrating conversations when we hire contractors to work in the house.

A couple of years ago I decided to get a cm tape measure, to make my life easier. It was hard to find a good quality tape with a cm scale on both edges (the inches + cm tapes are okay, except when you need to measure something left to right instead of right to left and the scale you want to use is on the wrong side of the tape from the edge you are trying to measure and mark). cm tapes just weren't available anywhere, that I could find. Finally ended up ordering a german-made tape from a specialty tool catalog.

And seriously, the weight of the rocket ought to be recorded on the flight card in newtons. The LCO is going to use the number for the thrust/weight calculations. Just makes sense, right? Otherwise there is all that 1lb ~ 4.5 newtons, 3.5 oz. ~ 1 newton fiddling around.

The Kilogram is dead?

That weighs heavily on me...

It does have massive implications...

The only concern I have is that they will take a similar approach to some of the EU when they switched to the Euro. The price stayed nearly the same but they just change the unit. Imagine a switch to Liters and paying the price of a Gallon - Talk about inflation.

cwbullet said:

The only concern I have is that they will take a similar approach to some of the EU when they switched to the Euro. The price stayed nearly the same but they just change the unit. Imagine a switch to Liters and paying the price of a Gallon - Talk about inflation.

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https://skeptics.stackexchange.com/...y-cause-prices-to-go-up-in-european-countries

It was a sector-by-sector thing. Restaurants, in particular, seem likely to exploit confusion about exchange rates to raise prices.

cwbullet said:

...I realize the article was mostly in gest.

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Not in jest so much as just really lazy. Popular-press articles about science-y things are generally pretty useless, but this one is a case of the "Igon Value problem"

https://rationalwiki.org/wiki/Igon_Value_Problem

So, I wonder if they'll redo the Candela yet again... If they are planning on it, I'd tell them to lighten up.

jlabrasca said:

https://skeptics.stackexchange.com/...y-cause-prices-to-go-up-in-european-countries

It was a sector-by-sector thing. Restaurants, in particular, seem likely to exploit confusion about exchange rates to raise prices.

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I will tell you it created a shock for me. The prices doubled overnight in some businesses. It was especially true in grocery stores.

cwbullet said:

I will tell you it created a shock for me. The prices doubled overnight in some businesses. It was especially true in grocery stores.

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Caveat emptor. We are fortunate indeed in the US that the CFPB is well-funded and fully-staffed to prevent such abuses <g>